Alkylthiopyrazines oxidation

Just as pyrazine. V-oxides may be converted into C-halogeno- (Section 4.1.3) or C-acyloxypyrazines (Section 5.5.2.3), so they can afford C-amino-, C-azido-, C-cyano-, or C-alkylthiopyrazines, although such reactions are not well developed yet. The following examples will illustrate such procedures as used in recent literature ... 

The oxidation of alkylthiopyrazines to alkylsulfonyl- and alkylsulfinylpyrazines (e.g., 11 and 12, respectively) has been described in Section 5A, and cleavage of 2-methyl-6-methylsulfonyl4/f-pyrazino[2,3-d] [1,3]oxazin4-one by guanidine (432)... 

A few such pyrazine derivatives have been made by primary synthesis (see Chapters 1 and 2) but the main preparative route is by oxidation of alkylthiopyrazines, discussed in Section 6.2.2.1. 

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